ArcGIS for Android(安卓)离线数据图例加载

图例是地图展示里常用的辅助展示工具。曾经我采用过将图例截成图片转为2进制保存到数据库里，然后在加载图层时候调取对应图片作为图例展示。但是后来知道geodatabase数据其实就是个空间数据库，如果是通过geodatabase数据加载图层，图斑都是geodatabase数据里的空间数据Geometry根据样式Symbol进行动态渲染，所以这个Symbol如果能提取出来，也就是我们要的图例了。根据这个思路，我找了找，果然找到了对应的方法，于是记录下来。

首先我们还是先初始化地图，并且加载图层：

mMapView=(MapView)findViewById(R.id.mapview);rvDownload=(RecyclerView)findViewById(R.id.rv_tuli);String path=StorageUtil.getSDCardRootPath(getApplicationContext())+"/ydyzt/data/GD_TDYT.geodatabase";Geodatabase localGdb=null;try {    localGdb = new Geodatabase(path);}catch (Exception e){    e.printStackTrace();}if (localGdb != null) {    for (GeodatabaseFeatureTable gdbFeatureTable : localGdb.getGeodatabaseTables()) {        if (gdbFeatureTable.hasGeometry()){            FeatureLayer layer = new FeatureLayer(gdbFeatureTable);            mMapView.addLayer(layer);        }    }}mMapView.setMapBackground(0xFAFAFA, 0xffffff, 0.0f, 0.0f);//地图背景

然后根据我们加载的图层获取对应的符号，然后将符号按照点，线，面类型转换成对应的Bitmap，而图例名称则取GeodatabaseFeatureTable里对应FeatureTemplate的名称，就构成了我们的图例：

Layer layer=mMapView.getLayer(0);tuliBeanList=new ArrayList<>();if(layer instanceof FeatureLayer){    String typeFileid= ((GeodatabaseFeatureTable)(((FeatureLayer)layer).getFeatureTable())).getTypeIdField();    if(typeFileid.equalsIgnoreCase("")){//TypeIdField没有值        //获取图层中的FeatureTemplate        List templates= ((GeodatabaseFeatureTable)(((FeatureLayer)layer).getFeatureTable())).getFeatureTemplates();        //从templates构造出图例        for(FeatureTemplate template :templates){            try {                //根据FeatureTemplate生成GdbFeature                GeodatabaseFeature feature= ((GeodatabaseFeatureTable)(((FeatureLayer)layer).getFeatureTable())).createFeatureWithTemplate(template, null);                Renderer renderer = ((FeatureLayer) layer).getRenderer();                //获取符号                Symbol symbol =  renderer.getSymbol(feature);                //得到代表图例的图片                Bitmap bitmap=createBitmapFromSymbol(symbol,layer);                String name=template.getName();                TuliBean bean=new TuliBean(name,bitmap);                tuliBeanList.add(bean);                //设置图例的布局和点击事件                // populateTemplateView(layerTemplate,bitmap,template,symbol,(FeatureLayer)layer);            } catch (Exception e) {                e.printStackTrace();            }        }        initTuli();    }else{//TypeIdField有值        List featureTypes= ((GeodatabaseFeatureTable)(((FeatureLayer)layer).getFeatureTable())).getFeatureTypes();        for(FeatureType featureType :featureTypes){            FeatureTemplate[] templates= featureType.getTemplates();            for(FeatureTemplate template :templates){                try {                    //根据FeatureTemplate生成GeodatabaseFeature                    GeodatabaseFeature feature= ((GeodatabaseFeatureTable)(((FeatureLayer)layer).getFeatureTable())).createFeatureWithTemplate(template, null);                    Renderer renderer = ((FeatureLayer) layer).getRenderer();                    //获取符号                    Symbol symbol =  renderer.getSymbol(feature);                    //得到代表图例的图片                    Bitmap bitmap=createBitmapFromSymbol(symbol,layer);                    String name=template.getName();                    TuliBean bean=new TuliBean(name,bitmap);                    tuliBeanList.add(bean);                    //设置图例的布局和点击事件                    //populateTemplateView(layerTemplate,bitmap,template,symbol,(FeatureLayer)layer);                } catch (Exception e) {                    e.printStackTrace();                }            }            initTuli();        }    }}

符号转换Bitmap的方法为：

//根据Symbol和Layer来创建相对应的图例private Bitmap createBitmapFromSymbol(Symbol symbol,Layer layer) {    Bitmap bitmap=null;    Geometry.Type type= ((FeatureLayer)layer).getGeometryType();    //跟不同的Type来创建不同的图例    if(type.equals(Geometry.Type.POINT)){//点图层        Point point=new Point(20, 20);        bitmap= SymbolHelper.getLegendImage(symbol, point, 50, 50, Color.WHITE);    }else if(type.equals(Geometry.Type.POLYLINE)){//线图层        Polyline polyLine=new Polyline();        polyLine.startPath(0,0);        polyLine.lineTo(40,40);        bitmap=SymbolHelper.getLegendImage(symbol, polyLine, 50, 50, Color.WHITE);    }else if(type.equals(Geometry.Type.POLYGON)){//面图层        Polygon polygon=new Polygon();        polygon.startPath(0, 0);        polygon.lineTo(250, 0);        polygon.lineTo(250, 100);        polygon.lineTo(0, 100);        polygon.lineTo(0, 0);        bitmap= SymbolHelper.getLegendImage(symbol, polygon, 250, 100, Color.WHITE);    }    return bitmap;}

最后将获取到的图例展示出来：

baseRecyclerAdapterOfflineData=new BaseRecyclerAdapter(this,tuliBeanList) {    @Override    public int getItemLayoutId(int viewType) {        return R.layout.item_tuli;    }    @Override    public void bindData(RecyclerViewHolder holder, int position, TuliBean item) {        TextView tvName=holder.getTextView(R.id.tv_tuliname);        ImageView ivTuli=holder.getImageView(R.id.iv_tuli);        tvName.setText(item.getTuliName());        ivTuli.setImageBitmap(item.getBitmap());    }};rvDownload.setAdapter(baseRecyclerAdapterOfflineData);rvDownload.setLayoutManager(new LinearLayoutManager(this));rvDownload.setItemAnimator(new DefaultItemAnimator());

看看最后的效果：

demo下载地址：http://download.csdn.net/detail/bit_kaki/9926236

参考文章：http://blog.csdn.net/yifei1989/article/details/17339095

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